Function Excel VBA自定义项格式-计算前更改参数值

我试图在Excel VBA中编写一个公式来计算：RR=（（a/（a+B））/（C/（C+D）））

当四个参数（A、B、C、D）中的任何一个为0时，我想在计算中将它们的值更改为0.5

有没有一个简单的方法可以做到这一点？我相信我的格式是错误的，或者我是走错了路。任何有用的提示都将不胜感激

我试过：

Function RR(A, B, C, D) As Double
If A = 0 And B = 0 Then
        A = 0.5
        B = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    ElseIf A = 0 Then
        A = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    ElseIf B = 0 Then
        B = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    ElseIf C = 0 Then
        C = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    ElseIf D = 0 Then
        D = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    ElseIf A = 0 And D = 0 Then
        A = 0.5 And D = 0.5
        RR = ((A / (A + B)) / (C / (C + D)))
    Else:  RR = ((A / (A + B)) / (C / (C + D)))
    End If 
End Function

试试这个：

Function RR(A, B, C, D) As Double
    If A = 0 Then A = 0.5
    If B = 0 Then B = 0.5
    If C = 0 Then C = 0.5
    If D = 0 Then D = 0.5
    RR = ((A / (A + B)) / (C / (C + D)))
End Function

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谢谢您！这很有效。我保持了整个等式不变，它工作得很好。